Ammeter frame



can 2, 1928.

' J. E. ESHBAUGH AMMETER FRAME Filed NOV. 30, 1927 gmeqa fiqse Patented Get.

"mire 'rr JESSE E. ESHBAITGH, OF FLINT, MICHIGAN, ASSIGNOR TO A C B? E PLUG CO, OBELINT, MICHIGAN, A 000 LION OF MIOHIG.

summer. a i

that the instrument have a uniform calibra-.

tion scale or, in other words, that equal'in crements of current passing through the instrument will cause equal increments of pointer deflection.

t is an object of the invention to provide an ammeter of the character described which is composed of a minimum number of parts. I accomplish this result by making the conductor, magnet su port, pointer support and dial support all rom a single stamping. I thus provide an ammeter which is very simple in construction and of which the cost of production is reduced to a minimum.

A further object of the invention is to provide an ammeter in which the conductor frame is formed of a single stam ing on which the permanent magnet and sha t carrying the armature and needle may be carried with no fastening means other than the parts of the conductor frame bent over to hold them firmly in their proper position.

. Other objects and advantages of the invention will appear in the course of the following description taken in'connection withithe accom anying drawing and appended claims.

In t e drawing: a

Figure 1 is a rear end view of the assembled ammeter mechanism.

Figure 2 is a plan view of the mechanism with the dial removed.

downward to provide a leg 14. and forward to provlde a base 16. Each wing 12 is formed on its rear side witha downward and forward extending clip or tab 18 for supporting one of the rear ends of a horseshoe magnet, as

described below. Formed integrally with the rear side of the central portion 10 is a tongue 20 which is curved downward and under the central ortion 10, where the tongue is prick punche as at 22, for providing a bearing surface for oneof the pointed ends of an armature shaft, as described below 1t will be understood, of course, that the under side of the central portion 10 issimilarly prick punched directly above unch 22 for reception of the other end of t e armature shaft.

At the bend connecting each wing 12 and leg 14, the conductor frame is out about half way across on the outer or non-adjacent sides and the metal of each leg 14 bent forward, as at 24, to provide slots for receiving the sides of the horseshoe magnet.

Supported on the conductor frame is a horses oe magnet which comprises a bight 26 and side ortions or arms 28. It will be noted that t e arms 28 converge toward the rear and beneath the wings 12 of the conductor frame, the inner side of the intermediate portion of each arm resting within the corresponding slot formed by cutting and turning down the portion 24 of the leg 14, and the end of each arm being-held by one of the tabs Fixed on the upper side of the central por- Resting on the wings 12 and tufting plate 30 is'the dial 34 which may beof any usual material, such as a non-magnetic metal, cardboard, etc. Since the dial is of usual construction and covers the entire mechanism of the ammeter, its outline only has been indicated in Figure 2, in dotted lines. Each wing 12 is provided adjacent its inner edge and spaced from the adjacent arm of the magnet with a hole 36 and extending through the holes 36 and corresponding holes in dial 334 are the rivets 38 which serve to hold the dial on the conductor frame. The dial has on its face the usual scale for indicating the deflection of the needle, described below, and 'isprovided with the usual arcuate slot 35 between and sli htly ahead of the rivets 38 and concentric wit the axis of the armature shaft (described below). Rotatably supported on the conductor frame between the under side of the central portion 10 and the tongue is the armature shaft 40 which is formed with cone-shaped ends fitting within the respective prick punched hearings in the central portion 10 and the tongue 20. Mounted on the shaft 40 is an armature 42 of'magne'tic material and beneath this is the needle or pointer 44 which is of very light thin material. Both the needle and armature extend in a pendicular to the shaft 40. Whi e the two elements may be held on the shaft in an usual way, I prefer to provide a very sma 1 soft metal washer 46 on the shaft 40 on each side of the armature and needle. These washers are pressed into position and serve to frictionally hold the needle and armature fixed on the shaft. The needle extends forward a short distance from the shaft 40, then upward at 48 throu h theslot 35, then forward in a plane paral e1 with the plane of the di 1. On 1ts rear end the needle is widened ou as at 50, for counterbalancing.

The bases 16 rest on a strip 51 of insulating material. Corresponding apertures are provided in each base 16- and in the strip 51 and extending through the apertures are the terminal bolts 54 for connection withm the circuit carrying the current to be measured. The bolts 54 are provided with nuts 56. The instrument late may be mounted in any usual way, eit er with or without a case, dependin on the character of the 1nstrument board used.

When the current passes through the conductor, magnetic lines of force are created about the conductor and the direction .and magnitude of this field of force is governed .by the direction and magnitude of the current. The tufting plate 30, being of magnetic material acts to distribute the magnetic field and causes-a uniform increase in field intensity per increment of current for a eater area about the conductor than would e possible with the conductor alone. The permanent magnet actsat all times to tend to hold the armature in the illustrated position. When a current is passing-through the conductor, the position of the armature is the resultant of the force of the permanent magnet tending to hold the armature in the illustrated position and the force of the electromagnetic lines of force about the conductor tending to cause the armature to assume a position at right angles to that illustrated. The amount of deflection is indicated by the position of the needle relative to the graduated scale on the dial.

I claim: a

1. In an ammeter, a conductor frame comprising a central portion and side wings lane perconnected therewith, each wing bein bent to provide a supporting base for attac ment therewith ofia terminal, a bent permanent magnet, means for supporting said magnet on said frame comprising a slot formed in each wing ad'acent the bend and a tab formed by bending t e metal of a wing over the edge of the magnet, and a shaft carrying a magnetic armature and needle mounted on said frame substantially equidistant from the polar projections of the magnet.

2. An ammeter unit comprising a conductor frame provided with a central portion and side wings, each wing being bent to provide a supporting base for attachment therewith of a terminal, a bent permanent magnet, means for supporting said magnet under said frame comprising a slot formed in each wing adjacent the bend and a tab formed by bending a portion of the wing about the edge of the magnet, a dial fixed to the upper side of said frame by an element extending through said frame spaced from the polar projections of the magnet, and a rotatable shaft carrying an armature and indicating needle supported on said frame substantially equidistant from the polar projections of said magnet.

3. In an ammeter, a conductor frame comprising a central portion and side win s, each side wing being bent to provide it 'eg for supporting said frame and for attachment of a terminal of an electric circuit each leg being provided with a notch on its outer side, and a horseshoe magnet having converging side portions positioned with a side portion in each notch, the end of each side port1on being engaged by a bent over portion of the adjacent wing.

In an ammeter, a conductor frame compllslng a central portion and side wings, means for conne'ctin said side wings to terminals of an electric circuit, a permanent horseshoe magnet positioned with an end adjacent each wing, means for fixing said ma net to said frame comprising portions of sald wings'bent tocontact the sides of said magnet, and a rotatable shaft carry'ng an armature and indicating needle supported by the central portion of said frame.

5. In an ammeter, a conduptor frame comprising -a central portion and side wings,

minals of an electrlc circuit, a permanent horseshoe magnet positioned with an end ad- I means for connecting said side wings-to terjacent each wing, means for fixing said magnet to said frame comprising portions of said Wings bent to contact the sides of said magnet, a dial supported on the upper side of said frame, and a rotatable shaft carrying an armature and indicating needle supported by the central portion of said frame and positioned to permit the position of the needle to be visible on said dial.

6. In an ammeter, a conductor frame com prising sidewings and a slightly depressed central portion, means for connecting said wings to the terminals of anelectric circuit, a permanent magnet beneath said frame and held thereto by bent portions of said wings, a soft metal tufting plate over the central portion of the conductor and extending downward on each side, a dial fixed to the upper side of said frame, and a rotatable shaft carrying an armature and indicating needle supported by the central portion of said frame and positioned so that the position of the needle will be visible on said dial.

7. In an ammeter, a conductor having a central portion and leg portions pro'ectmg downward for attachment to a suitable support, a dial carried by said conductor on the front side thereof, an armature pivotally mounted on the central portion of said conductor below the dial, a pointer associated with the armature and the dial, a tufting plate carried by the central portion of said conductor proximate to the armature, and a permanent magnet also carried by said conductor and adapted to hold the armature in predetermined position when there is no current flowing in the conductor.

8. In an ammeter, a metallic conductor frame comprising a central portion and side wings each having a portion bent at an angle therewith, the metal of said wings being cut on each outer side and bent back to form a slot, a horseshoe magnet having converging arms, each arm fitting within a slot, and means for holding said magnet against displacement compnsing a bent over portion of said frame.

In testimony whereof I aflix my signature.

JEssn ESI-I-BAUGH. 

